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where H 2 sal-sbdt are the Schiff bases formed between salicylaldehyde and dithiocarbazates) have been synthesised, and the structures of 1 and 2 revealed by X-ray diffraction analyses. The ligands coordinate in the tridentate ONS fashion out of the enethiolate tautomeric form. The potassium counterions, coordinated to water molecules, the phenolate-O, the oxo groups on vanadium and, in the case of 1, to the thiolate, provide interlinkages between the

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Reaction of trans-[PdCl 2 (DMSO) 2 ], cis-[PtCl 2 (DMSO) 2 ], and [Cu(OAc) 2 ] ¥ H 2 O with metronidazole (mnz) leads to the formation of new complexes, i.e., trans-[PdCl 2 (mnz) 2 ] (1), trans-[PtCl 2 (mnz) 2 ] (2), and trans-[Cu 2 (OAc) 4 (mnz) 2 ] (3), respectively. Complexes 1 ± 3 crystallize all in the centrosymmetric monoclinic space group P2 1 /c with Z 8. Unit-cell parameters for these complexes are: 1, a 7.1328(14) ä, b 20.699(4) ä, c 7.1455(14) ä, and b 116.17(3)8; 2, a 6.9169(14) ä, b 21.853(4) ä, c 6.7218(13) ä, and b 110.79(3)8; 3, a 9.1663(18) ä, b 19.129(4) ä, c 8.9446(18) ä, and b 116.44(3)8. The complexes 1 and 2 maintain an ideal square-planar geometry. In complex 3, the H 2 O molecules of the starting complex are replaced by metronidazole while maintaining a dimeric structure of [Cu(OAc) 2 ]. Each Cu ion has an ideal octahedral structure, though distortion occurs in the equatorial position where the acetato ligands are attached. The CuÀCu separation of 2.6343(8) ä indicates considerable metal-metal interaction.The testing of the antiamoebic activity of these complexes against the protozoan parasite Entamoeba histolytica suggests that compound 1 ± 3 might be endowed with important antiamoebic properties since they showed IC 50 values in a mm range better than metronidazole (Table 2). Thus, compound 1 displayed more effective amoebicidal activity than metronidazole (IC 50 values of 0.103 mm vs. 1.50 mm, resp.).

Reaction of [PdCl 2 (DMSO) 2 ], [PtCl 2 (DMSO) 2 ], and [RuCl 2 (h 4 -C 8 H 12 )(MeCN) 2 ] with S-acetyl N bacetyldithiocarbazate ( 2-acetylhydrazinecarbodithioic acid anhydrosulfide with ethanethioic acid; aadt; 1), S-3) led to new complexes [PdCl 2 (L)], [PtCl 2 (L)], and [RuCl 2 (h 4 -C 8 H 12 )(L)] (L ligands 1 ± 3). All these compounds were characterized by elemental analysis, IR, 1 H-and 13 C-NMR and UV/VIS spectra and thermogravimetric analysis. Ligand 1 coordinates through the thioxo S-atom and the carbazate N(b) atom, whereas in ligands 2 and 3 the thioxo Satom and the azomethine N-atom are coordinated to the metal ion. Screening of antiamoebic activity of these compounds was performed in vitro against the HK-9 strain of E. histolytica. All the complexes were more active than their respective ligands; compound 3a showed the most promising activity.